The invention concerns a method of adjusting a radio telephone system clock in relation to an associated transmitter/receiver station system clock, a frequency adjustment device to adjust the radio telephone system clock, and a radio telephone having such a frequency adjustment device.
According to the standard determined by ETSI for the European digital cordless telephone system (DECT), a portable telephone in locked idle mode is to resynchronize its timing in relation to its fixed part with at least a predetermined frequency.
A DECT signal is divided into time slots and frames, where a multiframe consists of 16 frames, and each frame consists of 24 slots (TDMA), each having 480 bits. Since the fixed part transmits data at a bit rate of 1.152 Mbits/sec., 184320 data bits will be transmitted during a multiframe. Even the best system clock (XO) will have an inaccuracy corresponding to at least 6-7 bits during such a period.